York Guard VI and defrost cycle

[Ralphy55]

My defrost board failed this spring and the old Yorkguard IV model had been discontinued and replaced by the Yorkguard VI, so I rewired things a little and installed the Yorkguard VI. No problems so far with the AC in the summer and the colder weather in the fall, but the last few days have been colder here and I'm concerned that the defrost cycle isn't programmed correctly since the outdoor unit seems to be freezing up. I have set the LCOT or low cuttoff point to be 15 degrees F and the defrost cycle to be 4, however I don't think that this is sufficient and the manual gives no indication as to whether to go higher or lower. The defrost works if I short the test pins, I think that I just need to set the correct cycle to solve my problem.

[dac122]

Just went through trying to figure out what all the pins and jumpers are on my Yorkguard IV so maybe I can help. So far I've not need the upgrade to VI (fingers crossed).

From my notes, the LTCO is just there to lock out the HP below that temp and always bring on aux heat, so I don't see it affecting defrost at all. 15 sounds good. Mines set to 10 and the tstat is set to 15 (I like having control from the house).

From my notes, at least on the IV, defrost is an algorithms built into the board looking at liquid line temp, ambient air temp with time factors. So this begs the question are temp sensors working and wired in correctly? Also have you ever seen the unit go into defrost on its own, as I'm not sure if a forced defrost from test pins exercises everything.

Finally York is pretty helpful so try calling them and see if they can put you in touch with some support.